In U.S. Pat. No. 6,840,854 issued Jan. 11, 2005 of Redekop is disclosed an apparatus for chopping and discharging straw from a combine harvester of the type which includes a plurality of blade members mounted on a hub for rotation about an axis of the hub with the blade members being arranged at spaced positions along the length of the hub substantially in radial planes of the hub so as to pass adjacent a plurality of axially spaced stationary blades again arranged in radial planes of the hub. The straw and other material discharged from the combine is fed into one side of the housing of the apparatus onto the hub and the material is carried around by the hub past the stationary blades in a chopping action. The material is then discharged from a discharge opening in the housing onto a tail board with spreading fins for spreading across the field.
Combine developments in recent years have put greater demands on the straw choppers and chaff spreaders. The main reasons are:
Larger combines and larger cutting widths are creating higher flows of straw and chaff;
Wider cutting widths create more demanding spreading widths;
Reduced tilling practices have put more demand on even spreading of both straw and chaff;
Plant breeding has resulted in tougher straw, higher yields and more residue;
Grain is often ready for harvest while the straw remains green;
The following problems can arise with existing technology:
When residue is not distributed evenly into a straw choppers by the threshing rotor(s) due to green, moist conditions it cannot be evenly distributed out of a chopper. Even with good distribution into a chopper, a traditional tailboard with fins does not do a good job distributing wet straw and chaff, often ending up with rows of undispersed green residue corresponding to each fin.
The best distribution performance in dry conditions is achieved with a tailboard since it is more power efficient, cost efficient and easier to set, dust is best controlled.
The best distribution in wet or green conditions is most often powered rotating discs.
Powered rotating discs do not work well in dry conditions in that they can provide uneven distribution in that long straw can be thrown farther, short straw and chaff when dry cannot be thrown far, leaving problems for spring seeding.
Currently a combine is purchased with either a powered rotating disc or a tailboard behind the straw chopper. The customer has to choose the option when he buys and, when harvest conditions change, they are stuck with the distribution method they chose.
In U.S. Pat. No. 6,663,485 assigned to Claas is disclosed the first power spreader brought to the market which has a discharge chute of chopper parallel with the spreader.
In U.S. Pat. No. 7,331,855 assigned to Deere is disclosed a powered Spreader at a 25 degree angle to residue flow. This is the first commercial successful power spreader which was developed for corn market to solve spreading of green stem soybeans where the plant remains green when grain is ripe.
The disclosures of all patents mentioned herein are incorporated herein by reference or may be referenced for further details not disclosed herein.